In microfluidics, in addition to the transport and processing of small amounts of gaseous or fluid substances, it is necessary to determine transported amounts as accurately and interference-free as possible. This is usually accomplished by measuring a fluid flow. However, the small size of the components requires an approach that is different from traditional constructions. In flow sensors that are designed as variants heating wire method, for example, short-circuits or interactions with conductive fluids may occur if insufficient passivation has been applied.
The heating wire method measures the flow of a fluid by heating, in a controlled manner, at one point and measuring the temperature increase of the fluid at a downstream temperature sensor, the flow velocity of the fluid being determinable from the temperature measured at the temperature sensor.